package com.example.surfacetest;

import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
		/** Called when the activity is first created. */
		Button btnSimpleDraw, btnTimerDraw;
		SurfaceView sfv;
		SurfaceHolder sfh;

		private Timer mTimer;
		private MyTimerTask mTimerTask;
		int Y_axis[],//保存正弦波的Y轴上的点
		centerY,//中心线
		oldX,oldY,//上一个XY点 
		currentX;//当前绘制到的X轴上的点

		@Override
		public void onCreate(Bundle savedInstanceState) {
			super.onCreate(savedInstanceState);
			setContentView(R.layout.activity_main);

			btnSimpleDraw = (Button) this.findViewById(R.id.button1);
			btnTimerDraw = (Button) this.findViewById(R.id.button2);
			btnSimpleDraw.setOnClickListener(new ClickEvent());
			btnTimerDraw.setOnClickListener(new ClickEvent());
			sfv = (SurfaceView) this.findViewById(R.id.SurfaceView);
			sfh = sfv.getHolder();

			//动态绘制正弦波的定时器
			mTimer = new Timer();
			mTimerTask = new MyTimerTask();

			// 初始化y轴数据
			centerY = (getWindowManager().getDefaultDisplay().getHeight() - sfv
					.getTop()) / 2;
			Y_axis = new int[getWindowManager().getDefaultDisplay().getWidth()];
			for (int i = 1; i < Y_axis.length; i++) {// 计算正弦波
				Y_axis[i - 1] = centerY
						- (int) (100 * Math.sin(i * 2 * Math.PI / 180));
			}
		}

		class ClickEvent implements View.OnClickListener {

			@Override
			public void onClick(View v) {

				if (v == btnSimpleDraw) {
					SimpleDraw(Y_axis.length-1);//直接绘制正弦波
				
				} else if (v == btnTimerDraw) {
					oldY = centerY;
					mTimer.schedule(mTimerTask, 0, 5);//动态绘制正弦波
				}

			}

		}

		class MyTimerTask extends TimerTask {
			@Override
			public void run() {

				SimpleDraw(currentX);
				currentX++;//往前进
				if (currentX == Y_axis.length - 1) {//如果到了终点，则清屏重来
					ClearDraw();
					currentX = 0;
					oldY = centerY;
				}
			}

		}
		
		/**
		 * 绘制指定区域
		 */
		void SimpleDraw(int length) {
			if (length == 0)
				oldX = 0;
			Canvas canvas = sfh.lockCanvas(new Rect(oldX, 0, oldX + length,
					getWindowManager().getDefaultDisplay().getHeight()));// 关键:获取画布
			Log.i("Canvas:",
					String.valueOf(oldX) + "," + String.valueOf(oldX + length));

			Paint mPaint = new Paint();
			mPaint.setColor(Color.GREEN);// 画笔为绿色
			mPaint.setStrokeWidth(6);// 设置画笔粗细

			int y;
			for (int i = oldX + 1; i < length; i++) {// 绘画正弦波
				y = Y_axis[i - 1];
				canvas.drawLine(oldX, oldY, i, y, mPaint);
				oldX = i;
				oldY = y;
			}
			sfh.unlockCanvasAndPost(canvas);// 解锁画布，提交画好的图像
		}

		void ClearDraw() {
			Canvas canvas = sfh.lockCanvas(null);
			canvas.drawColor(Color.BLACK);// 清除画布
			sfh.unlockCanvasAndPost(canvas);

		}
	}